The present invention relates to an electrical contact switch intended to be mounted, in particular, on a printed circuit board.
There are numerous applications for which industry seeks switches which combine reliability and constant switching force over a long life in a design that is simple, economical, and of small size.
Moreover, for certain applications it is necessary for the upper face of the switches to be illuminated internally. Mounting the switches in position must also be simple.
It is also desirable to have a modular switch which can easily be mounted on a previously prepared printed circuit board and whose structure is such that the function of the external housing of the switch is reduced merely to the function of masking and not the function of guiding.
There is known a push-button switch having a resilient element of rapid action, which is described in French Patent No. 2,468,197, which partially fulfills the above-mentioned conditions. Such a switch has a particularly long, useful life due to a special arrangement and to the use of a helical spring arranged transversely to the direction of movement of the push-button.
Although such prior switch has certain advantages, it also has disadvantages. There is no provision for illumination of the front face of the push-button. The switch has a pusher that is guided by the cover of the casing and by a fork in its lower part. The forces exerted on the push-button, when they are not precisely on the axis of the pusher, can bring about premature wear of the guiding means. Premature wear of the guiding means may lead to the introduction of foreign material inside the casing in the form of dust, which can lead to poor functioning of the switch.
A principal object of the present invention is to provide an electrical contact switch intended to be mounted on a printed circuit board, which overcomes disadvantages of the known switches.